I mostly agree with you, but...
in reply to Re: how did blocking IO become such a problem?
in thread how did blocking IO become such a problem?
As for the resistance of venerable old masters to threading, you'll have to ask them to know for sure, but in part it may be because the early threading libraries on *nix were rubbish; in part because it means learning something new.
Separate address spaces with explicit sharing are much easier to reason about than a single address space with implicit sharing. Accepting the latter in exchange for faster context switches is often a mistake.